I'll let Tim's own words (given us by Chuck Dixon) speak for themselves here; they set up the story quite well:

"So there's a gang of ninjas in Gotham...These aren't your sly assassins...they're burglars...Just second story guys with a gimmick. And they've been really lucky. Until last night. Last night one of them got killed" (Robin 21 pp 1-3). More specifically, he miscalculated a jump and fell to his death. Now that the plot's set-up, cut to Tim's house.

Mrs. McIlvaine (the housekeeper) catches Ariana asleep in Tim's bed! Of course, Tim was very honorable and slept in the guestroom himself, and she was only sleeping over due to trouble at home. We also now learn, while Tim is trying to explain to dad, that dad and physical therapist Dana are now shacking up. Ari then storms out abruptly.

Cut to the Batcave, where Robin is lamenting the entire Ariana situation to Alfred. With her uncle moving the family out of town, the future does not look too bright. At which point Batty drops in and orders a patrol. Which is good, because it leads our intrepid hero into the plot set-up from before, adding that Robin, as Tim, knows the dead ninja from school -- fellow student Ronnie Skipp. At Ronnie's funeral he finds out about a ninja training camp from Ronnie's sister.

Robin then follows a lead, one of Ronnie's friends who joined him in camp, and hits paydirt -- trailing the kid to a ninja rendezvous and burglary session, where he makes easy time with them until they pull a gun, which is where Robin plays smart and gets away before getting dead.

The next day brings Tim and dad another heart-to-heart where we learn that dad and Physical Therapist Dana are pretty darn serious and that Tim should get used to her being around. To which Tim uses as an advantage for getting dad to send him to the ninja camp.

First day at ninja camp... we learn that Phil "Dragoncat" Parsons runs the camp, and bullies the students relentlessly. We also learn that Phil's definitely the guy Robin went toe-to-toe with previously. We also learn that training at camp is completely remedial for Tim and he has to dumb himself, and his abilities, down in order not to look out of place (years from now, we see Dick doing the same thing in Police Academy). Tim's also being a good kid and looking out for his fellow trainees, to the point of blind-siding Parsons when he picks on an overweight asthmatic (pictured above). After beating Parsons up, Tim calls Ari. Nothing really important there, just more small talk about her eventual move

Turns out Tim's beating up Parsons was just what he needed to be let into the ninja burglar group. All he has to do is survive initiation: a 5K run through the woods, barefoot, while they hunt him. Tim decides to skip initiation, throw on his Robin togs and kick some booty. Which he does quite easily, and arranges to have the cops come get the rest. Our story ends with dad and Physical Therapist Dana picking up Tim and letting him know the Dzerchenkos were able to sell their stores. Bye bye Ariana.

(herein we pause to cry over my absence of the first part of Underworld Unleashed wherein Robin gets captured by the new and improved Killer Moth, who plans to eat our hero).

Open on Robin who is currently plastered up onto a ceiling thanks to Killer Moth's newfound abilities. After getting some info to and from Alfred, Robin busts loose just in time to defend himself from the moth, who's already been shown to shrug off bullets. Thankfully for Robin, another complete unknown shows up and saves him as he passes out. He wakes to Batman and no moth.

End on a nice segue into the next arc -- where we learn jock Karl Ranck has a problem with the "gangs" starting to move into their school and tries to recruit Tim into his group of vigilantes bent on keeping the gangs out.

After Tim turns Karl down, and runs to tell his dad about Karl's bringing a gun to school (right move, btw), Tim then has a heart-to-heart with Physical Therapist Dana where he basically gives her his stamp of approval.

From there, Tim Robin's up and teams up with Green Arrow II (Connor Hawke) for a little vigilante work against the gangs of their own. They rough them up pretty good until a gun is brought into it; lucky for them, Spoiler shows up and blinsides the gunman. While they do that, and Spoiler and Green Arrow introduce themselves to eachother, cut to Jack Drake, meeting with Mr. Ranck about Karl and his gun. That talk doesn't exactly go well, as Mr. Drake's not very good at convincing Mr. Ranck to take the gun away...

The Vigilantes Three get more leads, and have to adjourn for the evening, not having enough time to follow up on them until the next evening. Well, next day at school turns out Mr. Ranck DID do the right thing -- he took away Karl's gun, but he didn't do too hot keeping the guns locked up, because Karl just stole one of dear old dad's. While Tim is now reporting Karl to the principal, Karl's busy squaring off against the gang kids, shots are exchanged on both ends, and Karl ends up dead. Blinded by rage, Robin beats the pudding out of the gun-runners that night, so bad that Spoiler and Green Arrow have to peel him away before he kills them; and Robin comes to learn why "never fight angry" is as serious a rule as Batty makes it.

Karl Ranck gets a funeral, and Tim recaps in his head the tragic end of Karl. What else we get here is another important glimpse into the character of Ariana. Tim sees Stephanie Brown at the funeral and tries to avoid her. Ari gloms onto this and immediately goes into jealous girlfriend mode. The two make a scene about her, and Ari stomps off. Tim later witnesses Spoiler rough up some of Karl's friends who were at the shooting, and catches up to her as Robin. We learn the killer's name is Young El and the two set on his trail. While they find Young El and captre him, they now have to escape with him, which is easier said than done.Robin's in over his head this time, and if not for the timely intervention of Batman, he and Spoiler would have been killed.

After Batty sends Spoiler home and Young El to the cops, he and Robin have a nice chat. Batman feels disappointed that Robin didn't include him in his decision to bring in Young El, and gives Robin a little speech about teamwork, the symbolism of the bat-myth and justice.

Here comes the next Bat cross-over! With the Apocalypse Virus on the loose killing, Robin teams with Catwoman to track down the one man who might have the cure. They arrive there in time to get themselves messed up in a fight with both the Tracker and Azrael to boot. (Skip ahead 7 parts in the Contagion storyline to Robin's next issue) Tim apparently got the disease, and cured of it, in this empty space in the story, and since none of his supporting cast died either, not too much we missed... turns out Ari got sick, and then cured too. They both have an excited little telephone reunion, and both even say they love each other. After a foolish bout of rooftop hopping in his weakened state, Tim returns home to the shocking revelation that Ariana has dyed her hair blonde!

Tim HATES the hair, btw, but as any good boyfriend knows he should, he lies about how much he loves it. Like Tim really NEEDS a constant reminder of his conflicting emotions towards Steph every time he looks at his girlfriend, every time he thinks about his girlfriend, every time he kisses his girlfriend... and to make it worse, though she doesn't say it, Ari insinuates she did it because she wants Tim to view her on a much more physical level (she does admit it's also out of Steph-jealousy though).

Thank the gods Maxie Zeus comes to town.

Too bad Maxie's so slow, we get to see Tim complain about Ari's hair. First to his friends (to which Ives suggest he retaliate by getting a tattoo), and later to Nightwing, who is painted in his stereotypical hormone-ridden image, that thankfully, HE has outgrown by now. Though Nightwing does have one word of wisdom -- project your frustrations onto common thugs, which finally leads Robin on patrol and into a run-in with Maxie Zeus and his thugs.

While Robin's getting his butt whipped and captured by Maxie Zeus, Ariana agrees to go out on a "not like a date" with jock Jake Angstrom. So while Robin's tied up, and getting pressed for info on Oracle, because Zeus needs a seer, the nut, little miss "I love you" with a new hairdo is running around behind his back. Great.

Like a good little hostage, Robin's setting up the session between Oracle and Zeus, and escaping in the meantime. With help from a security guard, Robin buys enough time for the police to arrive and save the day. While all this is going on, Angstrom attempts to date-rape Ari, who narrowly escapes his evil clutches. Thankfully, this results in Ari going back to black hair.

Robin plus Impulse is next! Well, both Tim' class and Bart Allen's (Impulse) are headed to the nice snowy slopes for a bit of vacation. Granted, Tim and Alfred are also there to track down a crook named Vilk. Robin having met Bart earlier in the day, immediately recognizes him as Impulse when the two heroes meet later and move in on Vilk. The two boys are joined by new heroine calling herself Mystral. The villains cause an avalanche and make their escape.

Turns out Vilk is nuke hunting. More and more fighting ensues; Vilk kills his partner in crime. Vilk makes his escape then after setting up countdown to launch the nukes. With only three and a half minutes, it's all in Impulse's hands to come up with the right shutdown code out of trillions of combinations. Bart saves the day with a second ot two to spare. Mystral, meanwhile, captures Vilk.